High thyroid hormone level in early pregnancy linked to gestational diabetes

Women in early pregnancy who have high levels of the thyroid hormone triiodothyronine (T3) may be more than four times more likely to develop gestational diabetes, compared to women who have normal levels of the hormone, according to researchers at the National Institutes of Health.

The thyroid hormone triiodothyronine T3 is produced from the related hormone thyroxine (T4).

The researchers also found that a high T3/T4 ratio — which indicates a high conversion rate from T4 to T3 — was strongly associated with a higher risk for gestational diabetes.